Continuous Solvent Extraction of Transition Metals
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Solution Overview
Problem
Current methods for recovering and purifying transition metals like Mo, Tc, Ti, Ga, Sb, Zn, Sn, and Nb generate large volumes of secondary waste streams and require multiple steps, lacking a continuous protocol for efficient recycling of organic extraction liquors.
Innovation Solution
A continuous method involving acidification of highly alkaline solutions with HCl, followed by extraction using a neutral extractant like tri-n-butyl phosphate (TBP) to isolate transition metals in an organic phase, with subsequent washing and stripping steps to remove potassium and impurities, minimizing waste generation and achieving high recovery and purification efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional methods are used to separate 99mTc from Mo using potassium molybdate in potassium hydroxide, then 99mTc can be obtained, but large quantities of potassium are introduced that must be removed and large volumes of secondary waste streams are generated
Solution Approach 1:
The patent changes the chemical parameters by using ammonium hydroxide instead of potassium hydroxide as the base, and employing ammonium thiocyanate instead of potassium-based reagents. This parameter change eliminates potassium contamination while maintaining effective Mo and Tc separation, directly resolving the contradiction between separation efficiency and potassium contamination.
Solution Approach 2:
The patent recycles the ammonium-based organic extraction liquor back into the process, discarding only minimal waste streams. This recovery approach reduces waste volume significantly while maintaining separation efficiency, addressing both the waste generation and substance loss issues.
2Manufacturing precision
If multiple purification steps are used to remove contaminants from transition metals, then purity is improved, but the number of steps increases and productivity decreases
Solution Approach 1:
The patent combines multiple purification functions into a single solvent extraction step using ammonium-based reagents. This single step simultaneously achieves contamination removal, metal separation, and purification, eliminating the need for multiple sequential steps and thereby maintaining high productivity while ensuring metal purity.
Solution Approach 2:
The ammonium-based extraction system performs multiple functions simultaneously: it separates Mo from Tc, removes contaminants, and purifies the metal product in one integrated process. This multi-functionality resolves the contradiction by achieving high purity without requiring multiple separate steps.
3Ease of manufacture
If batch processing is used for metal extraction, then simplicity is maintained, but large quantities of metals cannot be processed efficiently and waste streams increase
Solution Approach 1:
The patent implements continuous counter-current solvent extraction where the organic extraction liquor flows continuously through the system, allowing large quantities of metals to be processed efficiently. The continuous operation maintains process simplicity while dramatically increasing productivity compared to batch methods.
Solution Approach 2:
The continuous recycling of the ammonium-based organic extraction liquor allows the system to process large metal quantities efficiently. The liquor is recovered and reused continuously, minimizing waste stream generation while maintaining high processing capacity, thus resolving the contradiction between simplicity and productivity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method achieves high efficiency in recovering transition metals with minimal secondary waste streams, enabling the processing of large quantities in a few steps, with over 97% Mo recovery in one extraction step and significant reduction of potassium impurities, suitable for medical isotope production.
Implementation Method 1
combining the solution with an organic liquid comprising a neutral extractant to extract the transition metals within the organic liquid
Implementation Method 2
the extractant does not function as a charged species (anion or cation), but acts as an agent to solubilize the neutral species in the organic diluent
Implementation Method 3
first acidification of highly alkaline molybdenum solution in acid (a myriad of acids are suitable, with HCl being used here for illustrative purposes)
Implementation Method 4
washing the extracted transition metals in the organic liquid with acid so as to remove potassium salt from the organic liquid phase
Implementation Method 5
contacting the washed organic liquid phase with hydroxide to remove the transition metals from the organic phase
Data Source
AI summary
The invention provides a continuous method for extracting transition metal, the method comprising: supplying a spent generator liquor comprising transition metal in highly alkaline solution; mixing the liquor with acid thereby generating a solution, wherein the transition metal resides within the solution; combining the solution with an organic liquid comprising tributyl phosphate or other neutral extractant to extract the transition metal within the organic liquid; washing the extracted transition metal in the organic liquid with acid so as to remove non-transition-metal salts from the organic liquid phase; and stripping the washed transition metal loadedorganic liquid phase with hydroxide, water or complexing agent to remove the transition metal from the organic phase.